Molecular Phylogeography and Intraspecific Divergences in Siberian Wildrye ( L.) Wild Populations in China, Inferred From Chloroplast DNA Sequence and cpSSR Markers.

A detailed understanding of the distribution and degree of genetic variation within a species is important for determining their evolutionary potential, which in return facilitates the development of efficient conservation strategies aimed at preserving adaptive genetic variation. As an important perennial, cool-season grass in temperate Eurasia, increasing attention has been paid to Siberian wildrye () due to its excellent ecological utilization value and forage production potential in China, particularly in the Qinghai-Tibet Plateau (QTP) regions. In this study, we applied two chloroplast (cp) genes ( and ), three cp spacer regions (-∼-, ∼, and ∼-), and six cpSSR markers to the genetic and phylogenetic analysis of 137 wild accessions from 23 natural populations that represent the main distribution regions in China. The results show the highest genetic diversity ( = 0.913) and haplotype richness (10 haplotypes) for the QTP population, which indicates QTP as the probable diversity center and geographic origin of in China. Population divergence was high, indicating a significant phylogeographic structure together with a significantly higher N value (N > G, < 0.05) at the species level, QTP+XJ (combined populations from QTP and Xinjiang), QTP+NC (combined populations from QTP and North China), and XJ+NC (combined populations from Xinjiang and North China) group levels, respectively. An expansion was revealed in the distributional range of in China from paleo times up to the recent past, while a dramatic range of contraction was predicted for the near future. The predicted main limiting factor for the further spread of is an increasing global mean temperature. We recommend that the combination of Es-cpDNA1 and Es-cpDNA3+4+5 can be used as effective markers for phylogenetic analysis and phylogeographical history analysis of . These findings shed new light on the historical population dynamics of cold-season herbs in the QTP region and the north of China and are of great significance for the future establishment of protection and collection strategies for wild germplasm.